Development of healthcare and social care services for the elderly population

Background & aim: The percentage of older people has been growing in all economically developed countries over the past several decades. The purpose of this research was to optimize the healthcare and social care model based on the in-depth study of social, hygienic and clinical characteristics of elderly individuals. Materials & methods: The authors' study included individuals aged 65 years and older. Results: The proportion of elderly and senile individuals increased from 15.3% in 2011 to 18.6% in 2020. The authors found that the existing healthcare system does not meet the needs of the aging population and thus developed a new organizational model for healthcare and social care services designed to integrate the activities of social welfare centers and local polyclinics. Conclusion: Implementation of the authors' model enables a range of healthcare and social care services and allows for management of a patient's health based on individual characteristics.

Laser-Induced µ-Rooms for Osteocytes on Implant Surface: An In Vivo Study

Laser processing of dental implant surfaces is becoming a more widespread replacement for classical techniques due to its undeniable advantages, including control of oxide formation and structure and surface relief at the microscale. Thus, using a laser, we created several biomimetic topographies of various shapes on the surface of titanium screw-shaped implants to research their success and survival rates. A distinctive feature of the topographies is the presence of "µ-rooms", which are special spaces created by the depressions and elevations and are analogous to the µ-sized room in which the osteocyte will potentially live. We conducted the comparable in vivo study using dental implants with continuous (G-topography with µ-canals), discrete (S-topography with μ-cavities), and irregular (I-topography) laser-induced topographies. A histological analysis performed with the statistical method (with p-value less than 0.05) was conducted, which showed that G-topography had the highest BIC parameter and contained the highest number of mature osteocytes, indicating the best secondary stability and osseointegration.

Pharmacokinetics of Angiotensin-Converting Enzyme Inhibitors in Elderly Patients with Arterial Hypertension

Objective: With the gradual aging of the world’s population, selecting an effective treatment regime for arterial hypertension (AH) becomes increasingly important. This article aims to analyze the pharmacokinetic and pharmacodynamic properties of parent enalapril and generic drugs in elderly patients suffering from AH. Materials and methods: The study is randomized, implying random distribution of patients into study groups. The study was conducted in 2018 among 200 patients diagnosed with AH. All elderly patients (mean age 77.5 ± 1.5 years) were divided into two equal groups. Group 1 was prescribed 10 mg of original enalapril orally, and Group 2 similarly took 10 mg of generic enalapril. The blood pressure of all patients was measured 1, 2, 4, 6, 8, and 11 hours after dosing and one day after treatment. Also, blood samples were taken after blood pressure measurements. Results and Discussion: After 1 hour, differences between Groups 1 and 2 (p ≤ 0.001) were found at the level of 29.84 ng/1 ml for the original drug and 19.01 ng/1 ml for the generic. Further, these values were 38.2 ng/1 ml vs. 28.7 ng/1 ml (p ≤ 0.001) after 2 hours, 36.6 ng/1 ml vs. 26.5 ng/1 ml (p ≤ 0.001) after 4 hours, and 9.2 ng/1 ml vs 5.1 ng/1 ml (p ≤ 0.001) after 24 hours, respectively. The maximum concentration-time curve values for both medications corresponded to the period of 2 hours after administration. Conclusion:Thus, generics are much less effective as an antihypotensive medication than the original enalapril. Bangladesh Journal of Medical Science Vol. 21 No. 03 July’22 Page: 562-569

International links between Streptococcus pneumoniae vaccine serotype 4 sequence type (ST) 801 in Northern European shipyard outbreaks of invasive pneumococcal disease

BACKGROUND

Pneumococcal disease outbreaks of vaccine preventable serotype 4 sequence type (ST)801 in shipyards have been reported in several countries. We aimed to use genomics to establish any international links between them.

METHODS

Sequence data from ST801-related outbreak isolates from Norway (n = 17), Finland (n = 11) and Northern Ireland (n = 2) were combined with invasive pneumococcal disease surveillance from the respective countries, and ST801-related genomes from an international collection (n = 41 of > 40,000), totalling 106 genomes. Raw data were mapped and recombination excluded before phylogenetic dating.

RESULTS

Outbreak isolates were relatively diverse, with up to 100 SNPs (single nucleotide polymorphisms) and a common ancestor estimated around the year 2000. However, 19 Norwegian and Finnish isolates were nearly indistinguishable (0-2 SNPs) with the common ancestor dated around 2017.

CONCLUSION

The total diversity of ST801 within the outbreaks could not be explained by recent transmission alone, suggesting that harsh environmental and associated living conditions reported in the shipyards may facilitate invasion of colonising pneumococci. However, near identical strains in the Norwegian and Finnish outbreaks does suggest that transmission between international shipyards also contributed to those outbreaks. This indicates the need for improved preventative measures in this working population including pneumococcal vaccination.

Coating Gold Nanorods with Self-Assembling Peptide Amphiphiles Promotes Stability and Facilitates in vivo Two-Photon Imaging

Gold nanorods (GNRs) are versatile asymmetric nanoparticles with unique optical properties. These properties makes GNRs ideal agents for applications such as photothermal cancer therapy, biosensing, and in vivo imaging. However,...

Evaluation of Streptococcus oralis adhesion and biofilm formation on laser-processed titanium

To prevent implant-associated infections, surface modifications need to be developed that prevent bacterial colonisation and biofilm formation. In the present study, titanium surfaces were processed by nanosecond-pulsed laser ablation to generate a variety of different structures (anatase, rutile, Osteon, as well as Osteon additionally coated with silver and clove nanoparticles). Analysis of adhesion and biofilm formation of the oral pioneer bacterium Streptococcus oralis could demonstrate antibacterial properties of anatase surfaces. For clinical translation, the effect should be enhanced by further adaption and combined with the osseointegrative Osteon structure

[SEVERE INFECTIOUS DISEASE AS A PREDICTOR OF CRITICAL ILLNESS ENCEPHALOPATHY IN CHILDREN (CLINICAL CASE)]

In childhood, infectious diseases, as a rule, are generalized in nature with the development of urgent or critical conditions that require the transfer of the child to mechanical ventilation. A child's stay on mechanical ventilation, on the one hand, is vital, on the other hand, it is a factor that threatens the development of acute encephalopathy, mechanical ventilation associated pneumonia, polyneuropathy and myopathy of critical conditions. According to the authors, the incidence of critical encephalopathy in patients with generalized infectious diseases who are on mechanical ventilation is 75%, and in the long-term (after 1 year) outcome in convalescents, the frequency of neurological deficit reaches 33%. In this regard, it is extremely important to timely diagnose and predict encephalopathy, including in children, as well as early adequate therapy with the inclusion of a complex action drug Cytoflavin, which has not only an antioxidant, antiplatelet effect, but also anti-inflammatory and remyelinating. The article presents a clinical case of critical state encephalopathy, which developed against the background of a severe infectious disease after artificial ventilation with effective timely use of Cytoflavin.

AB0864-HPR INFLUENCE OF THE TYPE OF PAIN SYNDROME ON THE SEVERITY OF ANXIETY-DEPRESSIVE DISORDERS IN PATIENTS WITH RHEUMATOID ARTHRITIS

Background:

Rheumatoid arthritis (RA) is a chronic autoimmune disease that leads to joint damage and deformation. Pain syndrome, along with functional limitations, causes the emergence of anxiety-depressive disorders. The patient’s psycho-emotional characteristics affect the patient’s quality of life and the effectiveness of the therapy. The aim: to assess the severity of anxiety and depression in women with rheumatoid arthritis, depending on the type of the pain syndrome.

Objectives:

The study included 163 women with RA according to the EULAR / ACR 2010 criteria (age 53,9 ± 10,15 years, RA duration - 10 [4; 14] years, DAS28 – 5,03 [4,35; 5,8]).

Methods:

We used the Hospital Depression and Anxiety Scale (HADS) questionnaire: 0-7 points were assessed as the absence of significant symptoms of anxiety and depression, 8-10 points - subclinically expressed anxiety and depression, more than 11 points - clinically expressed anxiety and depression. The severity of pain was determined by the VAS: no pain (0-4 mm), mild pain (5-44 mm), moderate pain (45-74 mm), severe pain (75-100 mm). Assessment of the type of pain (identification of the neuropathic component of pain) was carried out using the DN4 questionnaire: a sum of 4 or more points indicated the presence of a neuropathic component of pain (NCP). Statistical processing was performed using the STATISTICA 10,0 program.

Results:

The frequency of occurrence of anxiety-depressive disorders in RA patients was determined: clinically pronounced anxiety was detected in 35 (21,4%) patients, depression - in 34 (20,9%); subclinically expressed anxiety - in 42 (25,8%), depression - in 44 (27%) patients; absence of reliably pronounced symptoms of anxiety - in 86 (52,8%) patients, depression - in 85 (52,1%) patients.

Severe pain according to VAS was noted in 57 (35%) patients, moderate pain - in 75 (46%), in 31 (19%) patients the pain syndrome was mild. In 81 (49,7%) patients a neuropathic component of pain was revealed.

The relationship was established between the presence of NCP and the severity of anxiety (r = 0,27, p < 0,05), depression (r = 0,31, p <0,05). The relationship was revealed between the presence of NCP and the severity of pain according to the VAS (r = 0.32, p <0.05).

To explain the relationship between the presence of NCP and anxiety-depressive disorders, the patients were divided into two groups depending on the presence of NCP, comparable in age, the main clinical characteristics of RA, and basic therapy. The level of anxiety in women with NCP (9,5 [7; 13]) was significantly higher than in patients without NCP (6.1 [4; 9]) (p = 0.01). The severity of depression in women with NCP was 8,55 [6; 11], in patients without NCP – 5,15 [3; 6] (p = 0.005).

Conclusion:

Thus, every fifth patient with RA had clinically significance anxiety and depression, subclinical anxiety and depression were found in 26% of RA patients. Most of the patients (81%) had moderate or severe pain, half of the patients had signs of neuropathic pain. The relationship between the severity of anxiety and depression with the intensity of pain and the presence of a neuropathic component was revealed.

Disclosure of Interests:

None declared

Hydroxychloroquine in obstetric antiphospholipid syndrome: rationale and results of an observational study of refractory cases

BACKGROUND

The current recommended therapy of obstetric antiphospholipid syndrome (APS) is a long-term anticoagulant therapy that affects the final event, namely, when the thrombosis has already occurred. Unfortunately, this schedule is not always effective and fails despite the correct risk stratification and an adequate adjusted dose.

MATERIALS AND METHODS

From 2013 to 2020 we observed 217 women with antiphospholipid antibodies and obstetric morbidities who were treated with conventional treatment protocol (aspirin low doses ± LMWH). Among them 150 (69.1%) successfully completed pregnancy with delivery and live birth on the background of LMWH and aspirin therapy and in 67 (30.9%) women despite a traditional therapy regimen, obstetric complications were noted. Later, 56 of these 67 women became pregnant again and were offered traditional therapy plus hydroxychloroquine. Fifteen women refused HCQ treatment due to possible potential side effects. The final cohort consisted of 41 women with positive antiphospholipid antibodies and obstetric and thrombotic complications who received LMWH, aspirin low doses and HCQ at a dose of 200-400mg per day from the beginning of pregnancy.

RESULTS

Forty-one aPL women treated with HCQ after failed previous anticoagulant therapy had live births in 32 cases (78%). Adding of HCQ to the combination of LMWH and LDA showed good overall obstetric results and increased the number of live births in another 32 women. So, a total of 182 (83.8%) of initial 217 aPL-women ended their pregnancies with live birth after adding the HCQ to the traditional therapy with LMWH and low doses of aspirin.

CONCLUSION

In 20-30% of cases the live birth despite anticoagulation cannot be achieved. Perhaps APS is not just anticoagulation. The study of pathophysiological mechanisms suggests that some patients will benefit from other therapy (in addition to anticoagulant). Therapy that affects the early effects of aPL on target cells (monocytes, endothelial cells, etc.) or before binding to receptors-this therapy will be preferable and potentially less harmful than the officially accepted one to date. From this point of view, HCQ looks promising and can be used as an alternative candidate for women with refractory obstetric antiphospholipid syndrome. Adding HCQ should be considered in some selected patients with failed pregnancy after treatment with anticoagulants.

Photon Transport in a Bose-Hubbard Chain of Superconducting Artificial Atoms

We demonstrate nonequilibrium steady-state photon transport through a chain of five coupled artificial atoms simulating the driven-dissipative Bose-Hubbard model. Using transmission spectroscopy, we show that the system retains many-particle coherence despite being coupled strongly to two open spaces. We find that cross-Kerr interaction between system states allows high-contrast spectroscopic visualization of the emergent energy bands. For vanishing disorder, we observe the transition of the system from the linear to nonlinear regime of photon blockade in excellent agreement with the input-output theory. Finally, we show how controllable disorder introduced to the system suppresses nonlocal photon transmission. We argue that proposed architecture may be applied to analog simulation of many-body Floquet dynamics with even larger arrays of artificial atoms paving an alternative way towards quantum supremacy.

The Sociopsychological Profile of Persons with Alcohol Anosognosia in the Context of Social Customer Support

AIM: We aimed to focus on the sociopsychological profile of a person with alcohol anosognosia. METHODS: The study was conducted in the narcological inpatient adult department of the Starooskolsky Narcological Dispensary for 1.5 months and involved 60 male patients over the age of 18 with at least 5-year alcohol dependence. RESULTS: As a result of the study, the individual typological features of patients with anosognosia were identified and structured. CONCLUSION: The findings may be applied in the development of social support measures for persons with anosognosia to resocialize them and achieve long-term therapeutic remission.

AB0187 ASSESSMENT OF ADHERENCE TO TREATMENT OF PATIENTS WITH RHEUMATOID ARTHRITIS (RA)

Background:

Rheumatoid arthritis (RA) is the most common chronic immune inflammatory disease. The effectiveness of RA therapy largely depends on adherence to treatment. Non-compliance with the recommendations of the doctor leads to increased disease activity, a greater risk of complications and the increase in the cost of treatment.

Objectives:

To determine predictors of adherence to treatment of patients with RA.

Methods:

The study included 82 women with reliable RA according to the criteria of ACR1987 and / or EULAR / ACR2010 (mean age 53.3 ± 10.2 years, the age at the onset of the disease is 42.4 [36;51] years, mean duration of RA - 10.8 [6;14] years, DAS28 - 5.03 [4.3;5.8]). Treatment adherence was assessed according to the questionnaire “Quantitative Evaluation of Adherence to Treatment (KOP - 25)” [1]. The following indicators were calculated: adherence to drug therapy, adherence to medical support, adherence to lifestyle modification and their integral index. For all indicators, the level of values in the range up to 50% is interpreted as “low” («non-adherence to treatment»), from 51 to 75% - as “medium”, more than 75% - as “high”(«adherence to treatment»). The functional ability of patients was assessed by the Health Assessment Questionnaire (HAQ). The severity of pain was determined by VAS. Statistical processing was performing using the program STATISTICA 10.0.

Results:

Adherence to drug therapy in women with RA was determined: low adherence in 32 (39%) patients, average in 34 (41.5%) patients and high in 16 (19.5%) patients; adherence to medical support: low in 26 (31.7%) patients, average in 40 (48.8%) patients, and high in 16 (19.5%) patients; adherence to lifestyle modification: low in 55 (67%) patients, average in 25 (30.5%) patients and high in 2 (2.5%) patients. According to the integral indicator of adherence to treatment, 34 (41.5%) patients were not adherent to treatment, average adherence was recorded in 42 (51.2%) patients, and high in 6 (7.3%) patients.

The HAQ functional impairment was absent in 7 (8.5%) patients, minimal impairment occurred in 26 (31.7%), moderate - in 40 (48.8%) and severe - in 9 (11%) patients.

Severe pain in the VAS was noted by 29 (35.4%) patients, moderate - 39 (47.6%), in 14 (17%) patients the pain syndrome was weakly expressed.

The relationships of adherence to treatment was established with age (r = -0.29, p <0.05), age at the onset of the disease (r = -0.28, p <0.05), HAQ index (r = -0.27, p <0.05), the number of swollen joints (r = -0.3, p <0.05).

Patients under age of 39 years were the most adherence to drug therapy.

In patients with medium and high adhering to treatment, the severity of pain according to VAS was significantly lower than in non-adherent patients (50.6 [34;66] and 60.4 [46;73], respectively, p = 0.04), In patients with treatment adherence, activity was significantly lower than in non-treatment adherents (DAS 28 (4.7 [3.5;5.4] and 5.3 [4.7;5.9], respectively, p = 0.04).

Conclusion:

Low treatment adherence has 41,5% of RA patients. Predictors of adherence to treatment are the young age patients, the onset of the disease before age of 39 years. Non-treatment patients with RA have a higher activity of RA according to DAS28, pain intensity according to VAS, the worst functional status. To increase the effectiveness of treatment, constant interaction between the patient and the physician is necessary, explaining to patients the consequences of non-compliance with recommendations.

References:

[1]Nikolaev N. A., Skirdenko Yu. P. Russian universal questionnaire for the quantitative evaluation of adherence to treatment (KOP - 25). Clinical pharmacology and therapy. 2018;27(1): 74-78.

Disclosure of Interests:

None declared

Neonatal thrombosis

Neonatal thromboembolism in pediatric patients is a rare but life-threatening condition mainly caused by combinations of at least 2 prothrombotic triggering risk factors such as the central venous lines, septic condition, and prematurity. Other risk factors include asphyxia, dehydration, liver dysfunction, inflammation, and maternal condition. Neonatal hemostatic system is different from one of the older children and adults. Coagulation proteins do not cross the placenta but are synthesized in the fetus from an early stage. In the term neonate, concentrations of several procoagulant proteins, particularly the vitamin K dependent and contact factors are reduced when compared with adults. Conversely, levels of antithrombin, heparin cofactor II and protein C and S are low at birth and fibrinolysis system is characterized by the decreased level of plasminogen and alpha-1-antiplasmin, increased tissue plasminogen activator. These features all tend to be gestational dependent and are more present in the preterm infant. Primarily in this context neonates appear to be at a higher risk of thrombosis than older children. Thrombotic complications reach their peak in the group of children born at 22-27 weeks. The role of inherited thrombophilic risk factors in neonatal VTE development is poorly defined. The presence of inherited and acquired thrombophilia in mother and newborn is also responsible for the development of thrombosis in neonates and should be considered. Thrombophilia in the mother can lead to increased coagulation potential and prethrombotic conditions during pregnancy, causing thrombotic vasculopathy at the placental level. The benefit of identifying thrombophilia in the sick preterm newborns who are in the group of risk for development of thrombotic complications may facilitate the thromboprophylaxis. Further research regarding assessment of risk factors, diagnostics and treatment strategy is required.

The ESC ACCA EAPCI EORP acute coronary syndrome ST-elevation myocardial infarction registry

Aims 

The Acute Cardiac Care Association (ACCA)–European Association of Percutaneous Coronary Intervention (EAPCI) Registry on ST-elevation myocardial infarction (STEMI) of the EurObservational programme (EORP) of the European Society of Cardiology (ESC) registry aimed to determine the current state of the use of reperfusion therapy in ESC member and ESC affiliated countries and the adherence to ESC STEMI guidelines in patients with STEMI.

Methods and results 

Between 1 January 2015 and 31 March 2018, a total of 11 462 patients admitted with an initial diagnosis of STEMI according to the 2012 ESC STEMI guidelines were enrolled. Individual patient data were collected across 196 centres and 29 countries. Among the centres, there were 136 percutaneous coronary intervention centres and 91 with cardiac surgery on-site. The majority of centres (129/196) were part of a STEMI network. The main objective of this study was to describe the demographic, clinical, and angiographic characteristics of patients with STEMI. Other objectives include to assess management patterns and in particular the current use of reperfusion therapies and to evaluate how recommendations of most recent STEMI European guidelines regarding reperfusion therapies and adjunctive pharmacological and non-pharmacological treatments are adopted in clinical practice and how their application can impact on patients’ outcomes. Patients will be followed for 1 year after admission.

Conclusion 

The ESC ACCA-EAPCI EORP ACS STEMI registry is an international registry of care and outcomes of patients hospitalized with STEMI. It will provide insights into the contemporary patient profile, management patterns, and 1-year outcome of patients with STEMI.

Health Alliance for prudent antibiotic prescribing in patients with respiratory tract infections (HAPPY AUDIT) -impact of a non-randomised multifaceted intervention programme

Background

Excessive use of antibiotics is worldwide the most important reason for development of antimicrobial resistance. As antibiotic resistance may spread across borders, high prevalence countries may serve as a source of bacterial resistance for countries with a low prevalence. Therefore, bacterial resistance is an important issue with a potential serious impact on all countries. Initiatives have been taken to improve the quality of antibiotic prescribing in primary care, but only few studies have been designed to determine the effectiveness of multifaceted strategies across countries with different practice setting. The aim of this study was to evaluate the impact of a multifaceted intervention targeting general practitioners (GPs) and patients in six countries with different health organization and different prevalence of antibiotic resistance.

Methods

GPs from two Nordic countries, two Baltic Countries and two Hispano-American countries registered patients with respiratory tract infections (RTIs) in 2008 and 2009. After first registration they received individual prescriber feedback and they were offered an intervention programme that included training courses, clinical guidelines, posters for waiting rooms, patient brochures and access to point of care tests (Strep A and C-Reactive Protein). Antibiotic prescribing rates were compared before and after the intervention.

Results

A total of 440 GPs registered 47011 consultations; 24436 before the intervention (2008) and 22575 after the intervention (2009). After the intervention, the GPs significantly reduced the percentage of consultations resulting in an antibiotic prescription. In patients with lower RTI the GPs in Lithuania reduced the prescribing rate by 42%, in Russia by 25%, in Spain by 25%, and in Argentina by 9%. In patients with upper RTIs, the corresponding reductions in the antibiotic prescribing rates were in Lithania 20%, in Russia 15%, in Spain 9%, and in Argentina 5%.

Conclusion

A multifaceted intervention programme targeting GPs and patients and focusing on improving diagnostic procedures in patients with RTIs may lead to a marked reduction in antibiotic prescribing. The pragmatic before-after design used may suffer from some limitations and the reduction in antibiotic prescribing could be influenced by factors not related to the intervention.

Electron flow to photosystem I from stromal reductants in vivo: the size of the pool of stromal reductants controls the rate of electron donation to both rapidly and slowly reducing photosystem I units

Electron donation from stromal reductants to photosystem I (PSI) was studied using the kinetics of P700(+) (the oxidized primary donor of PSI) reduction in the dark after irradiation of barley ( Hordeum vulgare L.) leaves. The leaves were treated with diuron and methyl viologen to abolish both the electron flow from PSII and PSI-driven cyclic electron transport. The redox state of P700 was monitored using the absorbance changes at 830 nm (Delta A(830)). Two exponentially decaying components with half-times of about 3 s (the slow component) and about 0.6 s (the fast one) were distinguished in the kinetic curves of Delta A(830) relaxation after a 1-s pulse of far-red light. The complex kinetics of P700(+) reduction thus manifested two types of PSI unit differing in the rate of electron input from stromal reductants. The rates of both kinetic components assayed after 1-s pulses were increased about 20-fold by a short (2-5 min) heat-pretreatment of leaves, indicating the accelerated input of electrons to both types of PSI unit. The increased rates of electron flow to P700(+) were even observed 1.5 h after the action of heat had been completed. Both kinetic components were dramatically slowed down upon irradiation of heat-treated leaves for 20-30 s. Their rates were restored after a short (20-30 s) period of darkness. A 5-min leaf exposure at 38 degrees C was sufficient to stimulate by severalfold the reduction of P700(+) pre-oxidized by a brief light pulse. In contrast, the acceleration of P700(+) reduction after a 1-min irradiation was observed only if leaves were subjected to temperatures above 40 degrees C. Neither heat treatment of leaves nor light-dark modulations in the rates of the fast and the slow components of P700(+) dark reduction influenced the relative magnitudes of the two kinetic components, providing strong additional evidence in favor of two distinct types of PSI existing per se in barley leaves. The key role in the control of the activity of electron donation to P700(+) in both rapidly and slowly reducing PSI units was attributed to the amount of stromal reductants available for P700(+) reduction. The latter was expected to be reduced under illumination in the presence of methyl viologen, while increased again in the dark. The regeneration of the pool of stromal reductants in the dark was likely provided by starch breakdown within the chloroplast stroma, but not by import of reducing equivalents from the cytosol. This was evidenced by much lower rates, compared with 1-h dark-adapted leaves, of dark reduction of both components of P700(+) in leaves stored for 24 h in the dark and thus depleted of starch but containing large amounts of glucose, the respiratory substrate.

Relaxation of variable chlorophyll fluorescence after illumination of dark-adapted barley leaves as influenced by the redox states of electron carriers

Kinetics of the dark relaxation of variable chlorophyll fluorescence, Fv, were studied after brief illumination of dark-adapted barley leaves in order to understand the rapid reversibility of pulse-induced fluorescence increases, which is observed even when fast linear electron transport to an external electron acceptor is not possible. Four kinetically distinct components were observed which reveal complexity in the oxidation of the reduced primary quinone acceptor of Photosystem II, Q (A) (-) : the slowest component accounted for 4-5% of maximal Fv and had a life-time of several seconds. It is suggested to represent a minor population of inactive Photosystem II centers. The other three components displayed first-order kinetics with half-time of 6-8 ms ('fast' component), 60-80 ms ('middle' component) and 650-680 ms ('slow' component). The fast component dominated Fv when methyl viologen or far-red light accelerated oxidation of plastohydroquinone. It shows rapid oxidation of Q (A) (-) during electron flow to plastoquinone commensurate with maximum linear electron flow through the electron transport chain. The other two components were observed under conditions of restricted electron flow and excessive reduction of electron carriers. Unexpectedly, the slow component, which is interpreted to reflect the recombination between Q (A) (-) and an intermediate on the oxidizing side of Photosystem II, saturated already at low irradiances of actinic light when plastoquinone was not yet strongly reduced suggesting that dark-adaptation of leaves results not only in the loss of activity of light-regulated enzymes of the carbon cycle but affects also electron flow from Q(A) (-) to plastoquinone. KCN poisoning or high temperature treatment of leaves produced a nonexponential pattern of slow Fv relaxation. This effect was largely (heat treatment) or even completely (KCN) abolished by far-red light.